Correct Operation of BGP
Each UPDATE is intact, sent by the indicated sender, and is intended for indicated receiver
Neighbor that sent the UPDATE was authorized to act on behalf of its AS to advertise the routing information in the UPDATE to the BGP speakers in the recipient AS
Neighbor withdrawing a route is the advertiser for that route
AS that generated the initial UPDATE is authorized by the Organization that owns the address space in the NLRI to represent the address space